CODEWITHSUNDEEP
javascripthttprequestdetectionserver-side
aarona
aarona

Reputation: 37273

Why don't browsers send whether they have javascript enabled/disabled in the request header?

It just seems like something that would be really useful when developing server-side code. If you know that the browser won't be using javascript from the server-side, you could easily accommodate the user. Or if you just felt like it, redirect them to a page that says 'hey... we need you to use javascript for our application' etc.

Does anyone know why this is?

Upvotes: 6

Views: 3122

Answers (5)

Scott Warren
Scott Warren

Reputation: 1591

One way I use is to have a landing page/login page. When the user presses the logon button then use javascript to submit the results or update a hidden field before posting the logon. If javascript is disabled then the javascript will not work and therefore you can assume they have it turned off.

Upvotes: 1

jrn.ak
jrn.ak

Reputation: 36619

As handy as it would be to have your server be aware of your browser's Javascript capability before page rendering began, I can see a strange edge case such as:

// hide malicious code from people without javascript
if ($header['javascript'] == 'false') {
    show_regular_safe_website();
} else {
    use_some_nasty_javascript_exploit();
}

Upvotes: 1

JonC
JonC

Reputation: 978

I suppose the Accept field could be used to such a purpose, like "Accept: text/javascript". But since it's proprietary the IETF would never include it in any standards and widespread adaptation is therefore unlikely. Web-developers has coped so far.

Upvotes: -1

Gabe
Gabe

Reputation: 86718

The real reason is that when Netscape came out with JavaScript, they never thought to make the information available in the HTTP headers. Instead they created the <noscript> tag.

Upvotes: 0

Grant Thomas
Grant Thomas

Reputation: 45083

See the <noscript> tag, here.

I know it's probably not ideal (I don't have enough experience with it to pick it apart) but it certainly gives us enough flexibility to degrade somewhat gracefully.

Upvotes: 2

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